Vehicle guidance system

ABSTRACT

Apparatus is provided for automatically guiding a vehicle along a predetermined path in response to steer right, steer left, and steer without change signals obtained from trailing wheel apparatus following a precut trench. The trailing wheel is supported by a carriage assembly which is horizontally doublyarticulated and also pivotally connected to the vehicle for vertical travel. The carriage assembly includes a pair of limit switches and a vertically oriented pin normally positioned between the feeler arms thereof. Should the vehicle deviate sufficiently to one side of the predetermined path fixed by the precut trench, the carriage assembly shifts in such a manner that the pin touches one of the switch feeler arms to actuate the corresponding switch. An electrical signal developed therefrom institutes motor driven corrective action to the vehicle steering system, which corrective action is released once the pin is again oriented between the pair of feeler arms and touching neither. In the exemplary embodiment, the system is utilized to guide a farm tractor which may be provided with means to automatically cut guide trenches for a succeeding pass within an area where earth is being worked.

United States Patent [191 Sumida Mar. 19, 1974 1 VEHICLE GUIDANCE SYSTEM[76] Inventor: Harry H. Sumida, 10717 Antelope Dr., Lemoore, Calif.93245 22 Filed: July 13, 1972 [21 Appl. No.: 271,417

[52] US. Cl. ISO/79.1, 180/51 [51] Int. Cl B62d 61/00 [58] Field ofSearch 180/791, 51; 104/244.1

[56] References Cited UNITED STATES PATENTS 2,496,727 2/1950 Jenkins180/791 2,791,167 5/1957 Lockmiller ISO/79.1 X 2.674332 4/1954 Ovshinsky180/791 3.481.418 12/1969 Wallan 180/51 X 2,509,914 5/1950 Goodwine. Jr180/791 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-MichaelY. Mar Attorney, Agent, or Firm--Cahil1, Sutton & Thomas [57] ABSTRACTApparatus is provided'for automatically guiding a vehicle along apredetermined path in response to steer right, steer left, and steerwithout change signals obtained from trailing wheel apparatus followinga precut trench. The trailing wheel is supported by a carriage assemblywhich is horizontally doublyarticulated and also pivotally connected tothe vehicle for vertical travel. The carriage assembly includes a pairof limit switches and a vertically oriented pin normally positionedbetween the feeler arms thereof. Should the vehicle deviate sufficientlyto one side of the predetermined path fixed by the precut trench, thecarriage assembly shifts in such a manner that the pin touches one ofthe switch feeler arms to actuate the corresponding switch. Anelectrical signal developed therefrom institutes motor driven correctiveaction to the vehicle steering system, which corrective action isreleased once the pin is again oriented between the pair of feeler armsand touching neither. In the exemplary embodiment, the system isutilized to guide a farm t'ractorwhich may be provided with means toautomatically cut guide trenches for a succeeding pass within an areawhere earth is being worked.

3 Claims, 5 Drawing Figures PATENTEDMAR 1 9 I974 3; 797; 602

SHEET 2 OF 2 /9 I /8 wil vl VEHICLE GUIDANCE SYSTEM This inventionrelates to the vehicle guidance arts, and, more particularly, toapparatus for guiding a vehicle in accordance with the relative positionof the vehicle with respect to a prepositioned guide means such as aprecut trench.

Systems for remotely guiding vehicles under the direct supervision of anoperator or in accordance with some guide means which automaticallydescribes a path which the vehicle is to follow have been successfullyemployed for many years. Such systems have included ratio coupled remotecontrol units utilizing sophisticated servo means to insure properoperation. Similar systems electronically sense previously implantedguide means in conjunction with sophisticated steering means tofollowing a predetermined path. Less sophisticated systems, stillbasically electronic, use a simplified steering system having only steerright, steer left, and no steering correction facility. The lattersystems are used for less critical applications such as for slow movingvehicles, but they are of necessity complicated to the operator whomight realistically be expected to use such apparatus, and a break downrequiring repair becomes very serious if it should take place at acritical time. Additionally, experiences show that extraordinarymeasures must be taken to render such electronic equipment reliable inheavy duty use with consequent expense. Thus, it will be apparent tothose skilled in the art that it would be highly desirable to provide avehicle guidance system which is accurate, very rugged, simple andbasically mechanical in nature to circumvent the economic, operation,and cost drawbacks associated with more complicated systems typical ofthe prior art.

It is therefore a broad object of my invention to provide an improvedvehicle guidance system.

It is another object of my invention to provide such a system which issimple, rugged, and reliable.

It is yet another object of my invention to provide such apparatus inwhich the necessity for electronic circuits is obviated.

It is a more specific object of my invention to provide a vehicleguidance system including trailing wheel sensing means for following aguide trench It is a still more specific object of my invention toprovide such a system in which the trailing wheel sensing means includesa compound articulated carriage assembly carrying a pair of limitswitches for sensing, digitally, deviation from the prescribed path.

In another aspect, it is an ancillary object of my invention to providemeans within the system for preparing a guide path for a succeeding passof the vehicle as the vehicle follows the currently prescribed path.

The subject matter of the invention is particularly pointed out anddistinctly claimed in the concluding portion of the specification. Theinvention, however, both as to organization and method of operation, maybest be understood by reference to the following description taken inconnection with the accompanying drawing of which:

FIG. 1 is a perspective view illustrating an exemplary utilization ofthe apparatus of my invention to guide a tractor;

FIG. 2 is an exploded, partially cutaway view illustrating in moredetail the carriage assembly for the systems trailing wheel;

FIG. 3 is a partially cutaway top view of the carriage assemblyillustrating the relative disposition of various functional componentsthereof;

FIG. 4 is a side view of the carriage assembly further illustrating therelative disposition of the components; and

FIG. 5 is a schematic diagram of the electrical subsystem of myinvention.

Attention is now directed to FIG. 1 which, it will be understood, ismerely exemplary to illustrate the broad concepts of the invention.Those skilled in the art will understand, as the description of theinvention proceeds, that the positions of the various elements of thesystem may be adjusted according to the specific construction of thevehicle and the appliances used therewith. A conventional tractor lpulling earth working appliances such as the disc 2 is steered by areversible motor 3 which is coupled to the steering wheel 4 through aworm and follower speed reducer 5, universal joint 6, shaft 7, and rightangle drive 8. v

The reversible motor 3, through the conventional linkage between thesteering wheel 4 and the front wheels 9 of the tractor l, steers right,steers left, or steers without change according to the orientation ofcompound articulated carriage assembly 10 with respect to the tractor 1and to a precut guide trench 11. A trailing wheel 12 fixed to the afterend of the carriage l0 rides in the guide trench 11 to provideinformation representing the position of the tractor l with respect tothe guide trench 11 in a manner which will become apparent below.

Outwardly directed frame members 13 and 14 carry at their outer ends,respectively, trench cutting means 15 and 16 which function to cut guidetrenches, such as .the new trench 17 for receiving the trailing wheel 12on successive passes of the tractor 1 across the area to be worked. Thedistance between the center line of the tractor l and the trench cuttingmeans 15 and 16 may adjust according to the effective width of thespecific earth working apparatus such as a disc 2, utilized for a givenearth working operation. Similarly, it will be understood that thecentral trailing position of the carriage 10 is merely exemplary and, ifthe carriage 10 should be offset to one side or another, appropriate andobvious adjustment to the lengths of the frame members l3 and 14 may bemade.

Attention is now directed to FIG. 2 as well as FIG. I in order thatthemechanical features of the carriage 10 may be more clearly perceived.A vertical forward support member 18 is rigidly fixed to the tractor 1by any suitable means. Proximate the lower end of the support member 18is a cylindrical housing 19 fitted with bushings 20 at each end thereoffor receiving a bolt and nut assembly 21 which passes through apertures22 in fork member 23 at the forward end of the carriage It). Thus, thefork member 23, and hence the entire carriage 10, is pivotally fixed forrotation about the axis of the nut and bolt assembly 21. As a result,the trailing wheel 12 is free to following vertical undulations in theguide trench 1 1.

The fork member 23 includes a centrally disposed, vertically orientedcylinder portion 24 which is also fitted with bushings, similar to thebushings 29, but not shown, for fixing upper and lower horizontal framemembers, 25 and 26 for horizontal articulation about the axis of nut andbolt assembly 27 which passes through aligned apertures in the framemembers 25 and 26 and the bushings in the cylinder portion 24 of thefork member 23.

Similarly, proximate the rearward ends of the frame members 25 and 26, arearwardly extending U-shaped member 28 is utilized to support thetrailing wheel 12, and nut and bolt assembly 29 passes throughintermediate cylindrical portion 30 of the U-shaped member 28 to provideanother horizontally articulated joint in the carriage 10.

Stops 31 and 32 integral with the fork member 23 are positioned to abutthe edges 33 and 34 of the upper frame member 25 to limit the degree ofhorizontal movement about the axis of the nut and bolt assembly 27. Thenecessity for providing such limiting will become apparent as theoperation of the carriage 10 and its sensing apparatus is describedfurther. It may be noted that a switch mounting bracket 35 extendsrearwardly from the cylindrical portion 24 of the fork member 23.Switches mounted thereon, as will be discussed below, cooperate with apin 36 extending downwardly from the upper frame member 25 just forwardof the U-shaped member 28.

As shown in FIGS. 3 and 4, first and second limit switches 37 and 38 aremounted on opposite sides of the switch mounting bracket 35. Theswitches 37 and 38 are each provided with rearwardly projectingactuating feelers 39 and 40 which terminate just rearward of thedownwardly directed pin 36 which therefore normally is positionedbetween the feelers 39 and 40. However, as the carriage 10 pivots aboutthe axis defined by the nut and bolt assembly 27, the pin 36 moves withrespect to the feelers 39 and 40, toward one and away from the other,and if the movement is sufficient to bring the pin into contact with oneof the feelers, the corresponding switch 37 or 38 is actuated. In orderto prevent damage to the switches 37 and 38, the stops 31 and 32 limitthe possible pivotal movement between the fork member 23 and the framemembers 25 and 26 to an amount which just exceeds, in both directions,the amount of travel necessary to actuate the switches. Additionally,the feelers 39 and 40 are flexible to provide additional protectionagainst damaging the switches 37 and 38 which are themselves quiterugged. By way of example, precision limit switches manufactured underthe trademark Microswitch with a catalog listing 8LSl25 has been foundto be satisfactory for the intended purposes. Equivalent switches may,of course, be substituted.

The contacts of the switches 37 and 38 are normally open and thereforethere is no continuity between the conductors 41 and 42 or between theconductors 43 or 44 as long as the pin 36 is positioned intermediate thefeelers 39 and 40. However, when the switch 38 is actuated by physicalcontact between the pin 39 and 40 the normally open contacts are closedto electrically connect the conductors 41 and 42 directly. Similarly,physical contact between the pin 36 and the feeler 39 closes thecontacts of the switch 37 to electrically connect the conductors 43 and44. For convenience, the conductors 41, 42, 43, and 44 may be broughtout to a coupling 45 to facilitate removal from the adjustment to thetractor of the carriage 10.

The operation of the system will be readily understood from aconsideration of FIG. 5 in conjunction with the various mechanical andelectrical elements already described. As shown in FIG. 5, conductors 41and 43 are connected together and to one side of a battery 46 which maysimply be the battery included in the electrical system of thetractor 1. The other side of the battery 46 is connected to a commonterminal 47 of the reversing motor 3. Conductor 44 is connected to asecond terminal 48 of the reversing motor 3, and conductor 42 isconnected to a third terminal 49 of the motor. The characteristics ofthe reversing motor 3 are such that if the battery 46 is connectedbetween the terminals 47 and 48, it rotates in a first direction, and ifthe battery 46 is connected between the terminals 47 and 49, the motorrotates in the opposite direction. If the contacts of the switches 37and 38 as shown in FIG. 5, that is neither switch actuated, then thereversing motor 3 is not energized.

Assume now the condition generally depicted in FIG. 1 in which thetractor is closely following the guide trench 11. In that event, thetrailing wheel 12, and hence the carriage 10 follows in rather closealignment to the path of the tractor, and the pin 36 remains between,but not touching the feelers 39 and 40 although there will naturally bea limited amount of movement. However, consider now the events whichfollow should the tractor tend to veer slightly to the right. The errorin path will accumulate until the frame members 25 and 26 becomesufficiently angled with respect to the guide path 11 that the switch 38is actuated to energize the motor 3 by placing the battery 46 across theterminals 47 and 49. The motor 3 thereupon very slowly moves thesteering wheel 4 counterclockwise, through the previously describedlinkage, until the pin 36 backs away from the feeler 40. The very gentlenature of the correction avoids radical over correction, and the tractorl continues along a new, slightly corrected path determined by the resetposition of the steering wheel 4.

In the now obvious manner, if the tractor 1 tends to veer to the left,the switch 37 is actuated to throw the battery 46 across the terminals47 and 48 to bring about corresponding corrective steering back to theright until the switch 37 is reopened when the pin 36 falls off thefeeler 39.

By preparing an initial guide trench which includes appropriate turnsaccording to the lay of the area to be worked, the tractor 1 will followthe desired pattern without manual supervision other than starting andstopping which can be carried out directly or by very simple radiocontrol according to means already well known in the remote controlarts. It may be emphasized, as previously noted, that the incorporationof the guidance system according to the present invention into anysuitable vehicle is contemplated, and the description thereof in theenvironment of a farm tractor is exemplary of environments in which theinvention has provided eminently functional and practical.

While the principles of the invention have now been made clear in anillustrative embodiment, there will be immediately obvious to thoseskilled in the art many modifications of structure, arrangement,proportions, the elements, materials, and components, used in thepractice of the invention which are particularly adapted for specificenvironments and operating requirements without departing from thoseprinciples.

I claim:

1. An automatic system for guiding a vehicle in accordance with a precuttrench, said system comprising:

a. steerable wheel means for determining the vehicles direction oftravel;

b. a reversible electric motor;

c. mechanical linkage means including speed reducing means for couplingsaid motor to said steerable wheel means;

(I. trailing wheel means normally riding in the precut trench;

e. a carriage assembly fixed to the vehicle and supporting said trailingwheel at an aft end thereof, said carriage assembly comprising:

1. first doubly articulated pivotal means for permitting said wheel toremain in said trench should the path of the vehicle veer from the pathdictated by the precut trench, said first pivotal means including upperand lower frame members disposed intermediate forward and aft pivotmembers;

2. second pivotal means for permitting vertical movement of said wheelwith respect to said vehicle;

3. first and second normally open switches fixed to said forward pivotmember and having corresponding rearwardly directed first and secondfeelers; and

4. a pin disposed between said first and second feelers for actuatingsaid first switch and thus closing the contacts thereof if the vehicleveers beyond a predetermined angle in a first direction with respect tosaid guide trench and for actuating said second switch and thus closingthe contacts thereof if the vehicle veers beyond a predetermined anglein a second direction with respect to said guide trench; f. a source ofelectrical energy; and g. a plurality of conductor means electricallycoupling said source, said motor, and said switches whereby actuation ofsaid first switch energizes said motor to move said wheel means suchthat the vehicle is steered in the second direction, said motor beingde-energized when said first switch is no longer actuated, and wherebyactuation of said motor to move said wheel means such that the vehicleis steered in the first direction, said motor being de-energized whensaid second switch is no longer actuated. 2. The system of claim 1 inwhich said pin depends from one of said frame members.

3. The system of claim 1 in which rotational movement about said firstpivot member is limited in both directions by stop means.

1. An automatic system for guiding a vehicle in accordance with a precuttrench, said system comprising: a. steerable wheel means for determiningthe vehicle''s direction of travel; b. a reversible electric motor; c.mechanical linkage means including speed reducing means for couplingsaid motor to said steerable wheel means; d. trailing wheel meansnormally riding in the precut trench; e. a carriage assembly fixed tothe vehicle and supporting said trailing wheel at an aft end thereof,said carriage assembly comprising:
 1. first doubly articulated pivotalmeans for permitting said wheel to remain in said trench should the pathof the vehicle veer from the path dictated by the precut trench, saidfirst pivotal means including upper and lower frame members disposedintermedIate forward and aft pivot members;
 2. second pivotal means forpermitting vertical movement of said wheel with respect to said vehicle;3. first and second normally open switches fixed to said forward pivotmember and having corresponding rearwardly directed first and secondfeelers; and
 4. a pin disposed between said first and second feelers foractuating said first switch and thus closing the contacts thereof if thevehicle veers beyond a predetermined angle in a first direction withrespect to said guide trench and for actuating said second switch andthus closing the contacts thereof if the vehicle veers beyond apredetermined angle in a second direction with respect to said guidetrench; f. a source of electrical energy; and g. a plurality ofconductor means electrically coupling said source, said motor, and saidswitches whereby actuation of said first switch energizes said motor tomove said wheel means such that the vehicle is steered in the seconddirection, said motor being de-energized when said first switch is nolonger actuated, and whereby actuation of said motor to move said wheelmeans such that the vehicle is steered in the first direction, saidmotor being de-energized when said second switch is no longer actuated.2. second pivotal means for permitting vertical movement of said wheelwith respect to said vehicle;
 2. The system of claim 1 in which said pindepends from one of said frame members.
 3. The system of claim 1 inwhich rotational movement about said first pivot member is limited inboth directions by stop means.
 3. first and second normally openswitches fixed to said forward pivot member and having correspondingrearwardly directed first and second feelers; and
 4. a pin disposedbetween said first and second feelers for actuating said first switchand thus closing the contacts thereof if the vehicle veers beyond apredetermined angle in a first direction with respect to said guidetrench and for actuating said second switch and thus closing thecontacts thereof if the vehicle veers beyond a predetermined angle in asecond direction with respect to said guide trench; f. a source ofelectrical energy; and g. a plurality of conductor means electricallycoupling said source, said motor, and said switches whereby actuation ofsaid first switch energizes said motor to move said wheel means suchthat the vehicle is steered in the second direction, said motor beingde-energized when said first switch is no longer actuated, and wherebyactuation of said motor to move said wheel means such that the vehicleis steered in the first direction, said motor being de-energized whensaid second switch is no longer actuated.